Two accidents, two near accidents, one rudder

In researching the TWA 841 roll-over incident, all evidence thus far points to a problem with the rudder. Investigators, however, were following a red herring involving the #7 slat. After all, it was a glaring clue staring them right in the face — a large gaping hole on the right side of the aircraft where the #7 slat used to be. In the video below from the National Geographic channel and the series Mayday, the crashes of United Airlines Flight 585 in Colorado Springs and USAir Flight 427 in Pittsburgh are examined. Also covered is the near roll-over of Eastwind Flight 517. These three incidents all involve rudder hardovers.

Did a rudder hardover cause the TWA 841 upset? I haven’t been able to answer that at this point in my research, and I may never be able to say conclusively that it was a rudder hardover or rudder reversal, but all the clues I’m following are pointing at the rudder. Feel free to add your opinions. I’m open to all input.

Sorry, the video was pulled off of YouTube for copyright infringement. You can find the video on YouTube, but it is poor quality.

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I’m just an interested layman with an engineering background, but I would personally be very wary about drawing comparisons between the 737 hardover issue and this case. For one, the 737 uses a very different setup for the rudder PCU to that of the 727, and also because the 737 reversal/hardovers required a thermal shock component – heated hydraulic fluid entering a PCU valve considerably below freezing. This would be expected on approach – not in cruise as TWA841 was.

You are correct when you say that there is no comparison between the 737 rudder system and the 727 rudder system. What happened in the three rudder hardover cases mentioned in this post did not happen to TWA 841. The comparison being made is the end result of a rudder hardover and not the cause.

In the case of TWA 841, the rudder hardover was most likely caused by a yaw damper failure. See the posts “So what really happened” and “Overlooked clues.”

An excerpt from a comment by DW … September 20, 2013
“…. an engineering background … be very wary about drawing comparisons between the 737 hardover issue and this [TWA841] case….”

DW re’ that comment — keep in mind that the B737 upsets (COS and PIT) happened much later, even AFTER that Oct’90 “alpa” Petition suggesting that the Board consider “discrepant rudder” as an upset P.C. That 1984 Yorke- hypothesis was developed from mishap lessons of decades earlier, eg, AA Flight One, &ct.

During the investigator-confusion immediately following the mysterious B737 upset at KCOS/3Mar91, the early Mountain-Rotor scenario was popular, and had gone
mostly unchallenged, until alpa-UA investigators related the history of
Discrepant Rudder upsets aboard Boeing aircraft. Harold Marthinsen had distributed that Oct’90 “alpa” Petition to alpa pilot-investigators, who later worked that COS-upset investigation. It was those UA-alpa pilot-investigators who first educated the NTSB’s IIC [for the COS investigation] about historic discrepant-rudder upsets.

I have just finished viewing the CBS Classic documentary regarding Flight 841. A real nail-biter. My wife is Sasha Reynolds-Neu, who is reading your screenplay Scapegoat. We wish you immense success. Stories such as this need to be told.